Lubricating device

ABSTRACT

A lubricating device for gear trains ( 10 ), especially for wind power stations, includes at least two gear stages ( 16,18 ) that are disposed next to each other and are effectively interconnected, and a lubricant circuit ( 20 ) into which at least one filter unit ( 26 ) is mounted. To prevent stagnant resting zones for the lubricant from being created within the gear train housing including the gear stages, while ensuring that the entire lubricant that circulates in the gear stages is fed to the filter unit to be drawn off and filtered within predefined periods of time, the lubricant circulating inside the lubricant circuit ( 20 ) is discharged at one gear stage ( 18 ), is drawn off through the filter unit, and can then be fed to the other gear stage ( 16 ).

FIELD OF THE INVENTION

The present invention relates to a lubricating device for gear trains,especially for wind power stations, with at least two gear stageslocated next to one another, and dynamically connected to one another,and a lubricant circuit having at least one filter unit.

BACKGROUND OF THE INVENTION

Lubrication devices for gear trains in wind power stations are known andreadily available on the market. In the manner of closed circulatinglubrication, the lubricant, especially in the form of lubricating oil,is removed by gear oil pumps from the gear sump of the gear housing withthe gear stages, supplied to filtering by the filter unit, forfiltering, and discharged again to the interior of the gear housing toremove fouling, including in the form of metal shavings, from thelubricant. In spite of these measures, premature damage to the gears,which often occurs after six months, takes place in practicalapplications, both within the planet stage and on the spur wheel stagegenerally forming the two gear stages for the rotor of a wind powerstation. In particular, the planet stage often fails due to defectiveplanet bearings, as do the gear oil pumps of wind power stations due tometal shavings which occur with increased frequency in the lubricantcircuit. The reason for such failures is that within the spur wheelstage, due to the formation of resting zones with large areas for thelubricant (oil), it becomes possible for heavy metal particles to settlein those resting zones. Often lubricant or oil exchange takes place onlyin the area of the spur wheel stage so that lubricant exchange takesplace only conditionally, and contaminated or dirty lubricant can remainon the sides of the planet stage and can cause damage there.

SUMMARY OF THE INVENTION

An object of the present invention is to provide improved lubricationdevices that are reliable and economical in use, and ensure long-lastinggear train operation, thereby contributing to increasing the timebetween expensive maintenance intervals.

This object is basically achieved by a lubrication device where, on onegear stage, the lubricant circulating in the lubricant circuit is drawnoff, cleaned by the filter unit and then delivered to the respectiveother gear stage. Stationary resting or stagnation zones for thelubricant within the gear housing with the gear stages are avoided. Indefinable time intervals, all the lubricant circulating in the gearstages is delivered to the filter unit to be cleaned and filtered by it.For an average person skilled in the art in the area of lubricationdevices, especially in the area of wind power stations, it comes as asurprise that, with the measure of permanent circulation while avoidingstationary resting zones in the lubricant or gear oil bath, improvedpossibility for cleaning the lubricant flow by the filter unit isobtained. In particular, the heavy metal particles which otherwisesettle can be continuously supplied to the circulation process. Thisability leads to relief of the gear oil pumps and ultimately also of thegear stages, from which serious contaminants are removed. The pumps andgear stages can then perform their functions for a long time. Theimproved lubricant delivery at the respective gear stage alsocontributes to the extended performance.

In one preferred embodiment of the lubrication device of the presentinvention, provision is made such that in order to implement splashlubrication, the gear stages each individually and at least partiallypass through a type of immersion bath with a lubricant reserve. Thelubricant reserve has a subdivision such that each gear stage isassigned its own bath area. Preferably, the subdivision and thelubricant amount in the immersion bath are chosen such that overflowinglubricant from one gear stage with lubricant supply travels to the batharea of the following gear stage with lubricant removal. Thisconfiguration provides optimum lubrication of the gear stages within theimmersion bath of the lubricant, while still ensuring that within theimmersion bath lubricant displacement and the respective continuousdrawing off take place. Removal of fouling from the lubricant or gearoil bath is then achieved continuously.

In another, especially preferred embodiment of the lubrication device ofthe present invention, lubricant removal includes of a suction device,and the lubricant supply includes an injection device. In the gearhousing for the respective gear stage, the indicated devices are mounteddiagonally opposite one another, extending through the upper and lowerarea of the housing. Due to this diagonal configuration, optimumlubricant distribution within the gear stages takes place. The transittime for the lubricant between the gear stages from the injection sideto the suction side is likewise optimized.

Preferably, the gear stage comprises a planet gear and a spur gear. Bythe planet gear, it is possible to bring the rotor of the wind powerstation with its low rpm to higher rpm as required, to drive a generatorfor generating current or the like by the spur gear, in the knownmanner. For long-lasting and good lubricant operation, it has provenfavorable to provide injection of a cleaned lubricant for the planetgear and to implement suction for contaminated lubricant on the spurgear stage.

The filter unit used preferably in the lubrication device in thedirection of lubricant delivery has a fine filter which is safeguardedwith a bypass, followed by a coarse filter connected downstream inseries. Cleaning results are especially good when the filter fineness ofthe coarse filter is chosen to be approximately 5 to 10 times coarserthan the filter fineness of the fine filter. Such a preferably suitablefilter unit is described in DE 101 05 612 A1 of Hydac FiltertechnikGmbH.

The lubrication device of the present invention need not be limited togear stages in wind power stations. It can also be used for other gearstages and gear configurations, with and without planet gears.

Other objects, advantages and salient features of the present inventionwill become apparent from the following detailed description, which,taken in conjunction with the annexed drawings, discloses a preferredembodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the drawings which form a part of this disclosure:

FIG. 1 is a schematic, block diagram, not to scale, of a lubricationdevice according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The lubrication device is used for a gear train 10. The gear train 10shown in FIG. 1 is used in so-called wind power stations, in which arotor (not shown), driven by the force of the wind, delivers its outputpower to an input shaft 12. After passing through the gear train 10 therespective output power is delivered to an output shaft 14 which, forexample, can be connected to a generator (not shown) for generatingelectrical current. Since the rotor generally has very low rpm and thegenerator operation requires correspondingly higher input rpm, the geartrain provides a step-up ratio from low to high rpm by a factor i of forexample 1:80. The pertinent gear train assemblies for wind powerstations are conventional, and need not be described in further detail.

Such gear trains generally have two gear stages 16, 18, with each gearstage having several stage parts. In particular, the first gear stage 16includes planet gear and the second gear stage 18 includes a spur gear,with those stages also being referred to as the planet stage and thespur stage, respectively. The lubrication device of the presentinvention, in the manner of a closed circle or loop, has a lubricantcircuit 20. To propel the lubricant, a conventional motor pump unit 22is used, and is subsequently safeguarded in the lubricant delivery ordownstream direction by a check valve 24 of conventional design. Afilter unit 26 is connected subsequently or downstream between the motorpump unit 22 and the two gear stages 16, 18.

As illustrated in the block diagram, on the second gear stage 18, thelubricant circulating in the lubricant circuit 20 is removed and then issupplied via the motor pump unit 22 to the filter unit 26 before thelubricant cleaned in this way is then supplied to the first gear stage16. The lubricant circulation can be carried out independently ofwhether the rotor and accordingly the gear train 10 are in operation ornot. In this manner, by a control which is not detailed, the lubricantcan be cleaned even if the system itself is shut down, for examplebecause, with respect to the prevailing wind, operation of the systemwould not be profitable.

To implement splash lubrication for gear stages 16, 18 an immersion bath28 is provided having a definable lubricant reserve and into which thegear stages 16, 18 with their gear wheels are at least partiallyimmersed. A subdivision 30 is placed in the immersion bath 28, with eachgear stage 16, 18 thus being assigned its own bath area 32, 34 in theprocess. In particular, the subdivision 30 and the lubricant amount inthe immersion bath 28 are chosen such that the overflowing lubricant 36(see arrow representation) travels from first gear stage 16 withlubricant supply 38 to the second bath area 34 with the following gearstage 18 with lubricant removal or outlet 40 of the immersion bath 28.

In the selected embodiment, the lubricant removal 40 is formed with asuction device, while the lubricant supply 38 is formed with aninjection device. The suction and injection actions are adjustable bythe working capacity of the motor pump unit 22. In particular, theindicated injection device is configured such that, for the purposes ofa spraying-on process, parts of the first gear stage 16 are covered orfogged with the lubricant over a large area.

As also illustrated in FIG. 1, in the gear housing 10 for the respectivegear stages 16, 18, the devices 38, 40 are mounted diagonally oppositeone another. The lubricant supply 38 extends through the upper part ofthe housing 10. The lubricant removal 40, in the form of a suctiondevice, penetrates the housing area from the housing bottom. Withrespect to the diagonal configuration, it basically is also possible inone embodiment, which is not detailed, to supply the injection amount tothe top of the spur wheel stage and to implement suction on the bottomof the planet stage. Since the planet stage in terms of its support ishighly susceptible to fouling, it has proven advantageous to implementthe diagonal arrangement. As already described, diagonal fluid guidanceis promoted and improved in that the overflowing lubricant 36 is relayedfrom one bath area 32 into the other bath area 34 and then is availableto a filtration process by the filter unit 26. Sedimentation orsettling, especially of heavy fouling components such as metal shavingsor the like, in the bath area 32 is thus effectively controlled.

The filter unit 26 can be provided with a filter element. It has provenadvantageous to provide a fine filter 44 safeguarded with a bypass 42(spring-loaded check valve) in the lubricant delivery direction,followed by a coarse filter 46 connected downstream in series. In normaloperation, the fine filter 44 performs removal of fouling in thelubricant circuit 20. If the fine filter fail 44 fails, especiallyshould it be clogged with dirt, the bypass valve 42 opens and to thensupply the fluid flow to the coarse filter 46. Coarser dirt is thenretained by the coarse filter 46 and cannot penetrate into the geartrain 10 with its gear stages 16, 18 to cause damage. It has been foundto be especially favorable for this application if the coarse filter isdesigned to be 10 times more coarse than the filter stage of the finefilter 44. Thus, the fine filter 44 can have a filter fineness of 5 μmand the coarser protective filter can have a filter fineness of 50 μmparticle size. The pertinent, series-connected filter stages are priorart and it has proven especially effective to use filter units 26according to DE 101 05 612 A1 (corresponding to U.S. Pat. No.7,279,091).

By a combination of suction from the oil sump on the spur wheel area andinjection of lubricant into the planet stage after cleaning by thefilter unit 26, lubricant supply for the gear train parts of wind powerstations is achieved which ensures reliable and long-lasting,trouble-free operation even under harsh ambient conditions and with harduse.

The lubricant device of the present invention can be used by itself as amodular unit. It can also be installed as an additional system tostandard circulation lubrication or to immersion bath lubrication.Furthermore, the possibility also exists of integrating an additionalintake filter or intake screen (not shown) in the intake line to themotor pump unit 22 to protect the hydraulic pump against damage causedby dirt. Analysis of the contents of an intake screen yields conclusionsregarding wear processes in the gear train. The subdivision of the bathareas within the gear housing can also be formed by ribs or stiffenersof the gear housing. The planet stage 16 shown in FIG. 1 has so-calledplanet wheels which revolve around the sun wheel shown lowermost in theFIGURE. As viewed in the FIGURE, the internal geared wheel is shownuppermost. The structure of the planet gearing is conventional so thatit will not be described in further detail.

As shown in FIG. 1, a gear stage or planet stage 16 forms the planetgearing or the so-called planet part of the gear train. Conversely, twogear stage or spur wheel stages 18 form the actual spur gear which isalso called the spur part of the gear train. The diagonal lubricationconcept of the present invention for the lubrication device can also beused for gear trains with a different number of gear stages. The checkvalve 24 inserted downstream from the pump 22 is optional, and notabsolutely necessary. In particular the pertinent check valve 24 wouldbe suited for pressure limitation. The oil flow from the check valvecould then be routed to the intake side of the pump (not shown).

1. A lubricating device, comprising: first and second gear stagesmounted next to one another and dynamically connected to one another,said first gear stage having a planet gear, said second gear stagehaving a spur gear; a lubricant circuit having at least one filtertherein, having a lubricant supply for providing lubricant to said firstgear stage, having a lubricant removal for removing lubricant from saidsecond gear stage, and circulating lubricant drawn from said lubricantremoval to said filter for cleaning and then to said lubricant supply;and an immersion bath receiving individually and at least partially eachof said gear stages for said gear stages to pass through said immersionbath for splash lubrication of said gear stages, said immersion bathhaving a lubricant reserve and a subdivision separating said immersionbath into first and second bath areas for said first and second gearstages, respectively, said subdivision having a configuration and saidlubricant reserve having an amount such that lubricant overflows saidsubdivision to be conveyed from said first bath area to said second batharea, said first bath area having said lubricant supply, said secondbath area having said lubricant removal.
 2. A lubricating deviceaccording to claim 1 wherein said first and second gear stages are partsof a wind power station.
 3. A lubricating device according to claim 1wherein said lubricant removal comprises a suction device; saidlubricant supply comprises an injection device; and said first andsecond gear stages are mounted in a gear housing with said injectiondevice and said suction device being located diagonally opposite oneanother in an upper area and a lower area, respectively, of saidhousing.
 4. A lubricating device according to claim 3 wherein saidlubricant circuit comprises a motor pump unit conveying lubricantthrough said injection device, said suction device and said filter.
 5. Alubricating device according to claim 4 wherein said filter is mountedbetween said motor pump unit and said gear housing in said lubricantcircuit.
 6. A lubricating device according to claim 1 wherein saidfilter comprises a fine filter element safeguarded by a bypass and acoarse filter element connected in series to said fine filter elementdownstream in a direction of fluid flow through said filter.
 7. Alubricating device according to claim 6 where said coarse filter has afilter fineness approximately five to ten times greater than a filterfineness of said fine filter element.
 8. A lubricating device accordingto claim 1 wherein said filter comprises: a filter housing having alongitudinal axis, having a housing wall coaxial to said longitudinalaxis, and having a fluid inlet and a fluid outlet defining a flowdirection therein, said fluid inlet extending laterally through saidhousing wall; a first filter element within said filter housingextending along said longitudinal axis and having a first lengthessentially along an entire length of said filter housing; a bypassdevice within said filter housing openable to allow flow in said flowdirection without filtration through said first filter element; and asecond filter element within said filter housing and said first filterelement downstream of said first filter element in said flow directionhaving a second length not greater than one-half of said first length,said second filter element having a top end cap lying essentially in oneplane extending transversely to said longitudinal axis with a top end ofsaid fluid inlet, said first filter element having a first end adjacentto and encompassing said bypass device and an opposite second endadjacent to and encompassing said second filter element with a radialdistance therebetween, said second filter element having an end oppositesaid top end cap supported on a plate holder closing said fluid outletexcept for a passage in said plate holder.
 9. A lubricating deviceaccording to claim 1 wherein said filter comprises: a filter housinghaving a longitudinal axis and having a fluid inlet and a fluid outletdefining a flow direction therein, said fluid inlet extending laterallythrough said filter housing; a first filter element within said filterhousing extending along said longitudinal axis and having a first lengthessentially along an entire length of said filter housing; a secondfilter element within said filter housing and said first filter elementdownstream of said first filter element in said flow direction having asecond length not greater than one-half of said first length, saidsecond filter element having a top end cap lying essentially in oneplane extending transversely to said longitudinal axis with a top end ofsaid fluid inlet; and a bypass device within said filter housingopenable to allow flow in said flow direction without filtration throughsaid first filter element, said bypass device being a bypass valvehaving a closing part movable between open and closed positions openingand closing a flow path from said fluid inlet to said second filterelement without passing through said first filter element, respectively,and biased towards said closed position by a spring.
 10. A lubricatingdevice according to claim 1 wherein said filter comprises: a filterhousing having a longitudinal axis, having a housing wall coaxial tosaid longitudinal axis, and having a fluid inlet and a fluid outletdefining a flow direction therein, said fluid inlet extending laterallythrough said housing wall; a first filter element within said filterhousing extending along said longitudinal axis and having a first lengthessentially along an entire length of said filter housing; a bypassdevice within said filter housing openable to allow flow in said flowdirection without filtration through said first filter element; and asecond filter element within said filter housing and said first filterelement downstream of said first filter element in said flow directionhaving a second length not greater than one-half of said first length,said second filter element having a top end cap lying essentially in oneplane extending transversely to said longitudinal axis with a top end ofsaid fluid inlet, said bypass device being a bypass valve having aclosing part movable between open and closed positions opening andclosing a flow path from said fluid inlet to said second filter elementwithout passing through said first filter element, respectively, andbiased towards said closed position by a spring.